This innovative research is targeting the systematic development of miniature, selective, sensitive, stable, and fast Lambda sensors by controlling the grain size of the sensor material to nanoscale. The sensor envisioned is a resistance-modulating type of semiconductor gas sensor. The nanoscale powders have a high interface area per unit volume that leads to more effective use of materials for sensing applications. The high surface area also yields rapid equilibration and chemical diffusion essential for rapid response.
Nanocrystalline Ga2 O3 powder will be synthesized using two methods. This ceramic powder offers the most desirable properties at high temperature. Powders produced will be characterized to correlate the relationship between nanostructure and sensor performance. These powders will be used to produce flat plate sensors and multilayered sensors. Automated sensor-testing equipment that features computer automated control of A/F ratios, temperature, pressure, and flow in a test chamber will be used to determine sensor performance. Sensors will be characterized for sensitivity, selectivity, thermal stability, and mechanical robustness. For objective comparison, the developer will also prepare sensors from commercially available, coarser-grained precursors, and their performance will be evaluated. Some targeted specifications for the sensors include: suitability for high-temperature oxidizing and corrosive environments, temperature operating range of -40 to 900°C with spikes to 1,200°C possible, lifetime of 10 years, response time of 1 second or less, and compatibility with 12 V DC power supplies.